Secondary alcohol esters of hydroxyacids and uses thereof

Abstract

Secondary alcohol esters of hydroxyacids, e.g., ricinoleate esters of secondary alcohols, are prepared by reacting an ester of a hydroxyacid with a secondary alcohol, in the presence of an organometallic transesterification catalyst. Under these reaction conditions, a high proportion of the starting ester of a hydroxyacid is converted into a secondary alcohol ester of the hydroxyacid, while minimizing the formation of by-products including estolide. The product esters and composition containing same may be used as a lubricity agent or as a friction modifier in a lubricant composition.

What is claimed is:  
     
       1. A process comprising reacting an ester of a hydroxyacid with a secondary alcohol in the presence of a homogeneous organometallic transesterification catalyst, to form a secondary alcohol ester of a hydroxyacid wherein the catalyst comprises a metal selected from the group of metals having an atomic number of 13, 21-32, 39-51 and 71-84. 
     
     
       2. The process of  claim 1  wherein the ester of a hydroxyacid has the formula                    
       where each of R 1 , R 2 , and R 3  are hydrocarbon groups optionally substituted with one or more of halogen, oxygen, and nitrogen. 
     
     
       3. The process of  claim 1  wherein the secondary alcohol has the formula                    
       where each of R 4  and R 5  are hydrocarbon groups optionally substituted with one or more of halogen, oxygen and nitrogen. 
     
     
       4. The process of  claim 1  wherein the secondary alcohol ester of a hydroxyacid has the formula                    
       where each of R 2 , R 3 , R 4  and R 5  are hydrocarbon groups optionally substituted with one or more of halogen, oxygen and nitrogen. 
     
     
       5. The process of  claim 1  wherein the ester of a hydroxyacid has the formula                    
       the secondary alcohol has the formula                    
       the secondary alcohol ester of a hydroxyacid has the formula                    
       and each of R 1 , R 2 , R 3 , R 4  and R 5  are hydrocarbon groups optionally substituted with one or more of halogen, oxygen and nitrogen. 
     
     
       6. The process of  claim 5  wherein each of R 1 , R 2 , R 3 , R 4  and R 5  is independently selected from C 1 -C 22  hydrocarbon groups. 
     
     
       7. The process of  claim 6  wherein each of R 1 , R 2 , R 3 , R 4  and R 5  is independently selected from C 1 -C 22  aliphatic groups. 
     
     
       8. The process of  claim 1  wherein the ester of a hydroxyacid and the secondary alcohol ester of a hydroxyacid are each esters of ricinoleic acid. 
     
     
       9. The process of  claim 8  wherein the ester of a hydroxyacid is castor oil. 
     
     
       10. The process of  claim 1  wherein the catalyst comprises titanium or tin. 
     
     
       11. A process for preparing a secondary alcohol ester of a secondary hydroxyacid according to the formula (R 4 )(R 5 )CH—O—C(═O)—R 2 —CH(OH)—R 3 , the process comprising combining an ester of a secondary hydroxyacid with a secondary alcohol under transesterification conditions, the conditions comprising a homogeneous organometallic transesterification catalyst, where R 2 , R 3 , R 4  and R 5  are independently selected from C 1 -C 22  hydrocarbon groups optionally substituted with one or more of halogen, oxygen and nitrogen. 
     
     
       12. The process of  claim 11  wherein the ester of a secondary hydroxyacid has the formula (alkyl)—O—C(═O)—R 2 —CH(OH)—R 3 , wherein (alkyl) is an alkyl group. 
     
     
       13. The process of  claim 12  wherein (alkyl) is methyl. 
     
     
       14. The process of  claim 11  wherein the ester of a secondary hydroxyacid is selected from methyl ricinoleate and castor oil. 
     
     
       15. The process of  claim 11  wherein the secondary alcohol has the formula (R 4 )(R 5 )CH—OH, wherein each of R 4  and R 5  is independently selected from C 1 -C 22  hydrocarbons. 
     
     
       16. The process of  claim 15  wherein the secondary alcohol is selected from the group consisting of isopropyl alcohol, 2-butanol, cyclohexanol, and capryl alcohol. 
     
     
       17. The process of  claim 11  wherein the organometallic transesterification catalyst comprises a transition metal selected from titanium and tin. 
     
     
       18. The process of  claim 17  wherein the organometallic transesterification catalyst is a tin(II) salt of a carboxylic acid. 
     
     
       19. The process of  claim 17  wherein the organometallic transesterification catalyst is a tin (IV) compound.